The present invention relates to an apparatus for instantaneously stopping a reel of a slot machine driven in rotation by a stepping motor.
In a slot machine, for example, a three-reel type slot machine, a player can attempt to win a game by stopping each of the three reels, on the periphery of which symbols such as pictures or numerals are disposed, as they rotate at a high speed, so as hopefully to obtain a desired combination of the symbols at the present window position. Nowadays, it is common to rotate reels by means of stepping motors. Since the determination of the stopped symbols at the preset window position can be made based on the number of drive pulses supplied to the respective stepping motors during rotation thereof, this is a very convenient practice. In slot machines of this type, stopping of the reels is generally effected by terminating the supply of drive pulses to the stepping motors.
Moreover, multi-phase drive pulses are commonly used in the art to drive stepping motors. For instance, when using a two-phase drive energization circuit and generating therefrom four-phase drive pulses, drive pulses each offset in phase by 90 degrees are sequentially supplied to the stepping motor to drive it. To stop the stepping motor, the frequency of drive pulses supplied to each phase is gradually reduced from the time when a stop signal is generated, ultimately to terminate the supply of drive pulses to each phase.
In stopping the stepping motor in the above manner, it is a fairly long time from when the stop signal is generated to when the reel stops. Therefore, in a slot machine of the type generating a stop signal responsive to manipulation of a stop button by the player, the time when the stop button is manipulated is perceptibly different from the time when the reel actually stops, thereby detracting from the player's belief that he may accurately control the machine. Thus the time lag between manipulation of the stop button the actual reel stop page must be as short as possible.